School of Agriculture, Food and Ecosystem Sciences - Theses

Permanent URI for this collection

Search Results

Now showing 1 - 10 of 18
  • Item
    Thumbnail Image
    A study of the effects of high stocking rates on the production of perennial pasture and its utilization by dairy cattle
    Rogers, Graeme ( 1973)
    The work in this thesis consists of a study of the effects of increasing the stocking rate from 2.2 to 3.2 cows per hectare on the production of dairy cattle and perennial pastures from 1966-70. (a) Milk production per cow was significantly reduced (P < 0.05) by the increase in.:stocking rate with the exception of the first year. (b) The yield of milk and milk components per hectare was increased (P< 0.05) by the increase in stocking rate except for 1968-69 when a drought occurred and the increases were not large enough in most components to attain significance (P)00.05). The yield of nitrogen in milk per hectare was significantly increased (p<0.05) in all years with stocking rate. (c) There was a tendency for the high stocking rate to lower the percentage of all components in milk with the exception of nitrogen which remained unaltered. However significant differences were not recorded consistently in any one component over the four lactations studied. (d) No significant differences (p>0.05) in seasonal or annual net pasture production were recorded between stocking rates. (e) The increase in stocking rate caused significant increases (1).<0.01) in grazing pressure, reductions in pasture availability (P<0.01) and higher contents of crude protein (1).<0.01) in pasture excepting spring and on two occasions in winter. (f) Estimates of feed intake at the higher stocking rate showed a significant increase in pasture harvested (P < 0.01) per unit area every year. However with the exception of the first year feed intake per cow was significantly reduced (P<0.01). (g) The ratio of pasture consumed per hectare to milk production per hectare was not significantly affected (P>0.05) by the increase in stocking rate.
  • Item
    Thumbnail Image
    Some effects of botanical composition of pasture on the liveweight and wool production of sheep
    Reed, K. F. M (1942-) ( 1972)
    Until recently, the main evidence on which to base pasture mixture. recommendations in Victoria, has been district experience and the results from dry matter ( "mowing") experiments. The grazing experiments described in this thesis, were initiated by Messrs. R. Twentyman, R. Newman, R. Allen and K. Maher of the Department of Agriculture during the period, 1960-196. Their aim was to develop some objective appreciation of the relative value for animal production of some of the sown and unsown species in Western district pastures. In addition to pasture species evaluation, they sought information on the relationship between pasture growth and animal production. Such information is needed so that Agrostologists can better evaluate the many pasture management factors (such as fertilizers, seeding rates, seed. treatments, herbicides, insecticides and defoliation treatments) that affect pasture growth and for which advice is frequently sought.
  • Item
  • Item
    Thumbnail Image
    Studies on metabolizable energy values of poultry feedstuffs
    Guirguis, N ( 1974)
    This thesis describes studies carried out on metabolizable energy values of a number of feedstuffs available in the State of Victoria for poultry nutrition. These investigations were part of a research project in the poultry research section of S.S.Cameron Laboratory (Animal Research), Werribee. I was responsible for the design and execution of the experiments and for all chemical analyses. The statistical analysis was done by Mr. Jardine, Biometrician, Department of Agriculture, Melbourne. The interpretation of the results and the preparation of the review and the manuscript have been my responsibility. Chapter 1 includes a literature review of the different methods that are used in determining metabolizable energy values for poultry as well as the factors that may affect the metabolizable energy content of diets and feed ingredients. Chapter 2 describes the general procedure of the metabolizable energy assay. The specific material and methods of the experiments were included in each of the experimental chapters. Chapter 3 outlines the balance studies carried out to determine metabolizable energy values of various feedstuffs with different sexes. A comparison between the biologically determined values and those calculated from the chemical composition of the feedstuffs also was included. Chapters 4, 5 and 6 concern the investigations carried out to study the effect of sex of chicks on metabolizable energy content of soyabean, rapeseed, fish meals, tallow and sunflower oil at various levels of inclusion in diets. Chapter 7 summarises the results obtained and recommended avenues for future work. Note: The experimental chapters (3-6) are presented in the format required for publication in the Australian Journal of Experimental Agriculture and Animal Husbandry.
  • Item
    Thumbnail Image
    The utilization of livestock wastes by ruminants
    Hendrosoekarjo, Soepharno ( 1975)
    In studies with sheep faeces it was found that the longer the faeces were stored,the lower the content of moisture, crude protein and ether extract and the higher the content of nitrogen free extract. Crude fibre and ash contents were relatively constant. The in vitro technique and the in vivo nylon bag technique to estimate dry matter digestibility (DMD) and organic matter digestibility (OMD) of excreta were investigated. Using an oven as an incubator in the in vitro technique, DMD and OMD coefficients of the faeces of sheep, cattle, pig and the manure of poultry were 19.2, 18.9, 45.7 and 62.6,and 10.9, 8.6, 28.2 and 30.7, respectively. Using a waterbath as an incubator DMD and OMD coefficients were 18.8, 16.8, 31.3 and 53.7,and 17. 0, 14.6, 28.0 and 48.2, respectively. The different techniques are discussed. The in vivo nylon bag technique using nylon "A" in sheep and using nylon "A" and "B" in cattle was carried out for 24, 48, 72 and 96 hours incubation periods. DMD and ODM coefficients are recorded, and the procedures are described. The effects of continuous feeding for 70 days of dried pig faeces, supplemented in the diet of 21 sheep were studied. Seven dietary treatments were imposed. Diet A was a pelleted medium quality hay containing 10.3 mg Cu/kg DM and 0.2 mg Mo/kg DM. Diets B,C and D contained 15% pig faeces which gave a dietary Cu concentration of 101.3 mg/kg; molybdenum was added to diet C to give a concentration of 90 mg/kg DM and to diet D to give a concentration of 175.5 mg/kg DM. Diets E, F and G contained 30% pig faeces (192.5 mg Cu/kg DM) ; molybdenum was added to diet F to give a concentration of 90 mg/kg DM, and to diet G to give a concentration of 175.5 mg/kg DM. Sulphate was added to all diets at the rate of 1.08% of the dry matter. During the experiment all animals survived. Inclusion of dried pig faeces in the diets reduced the digestibility compared with the control diet. The maximum plasma GOT activity detected was 182 units/ml reading at 505 nm wavelength. Blood Cu concentrations ranged from 0.28 ug/ml to 3.50 ug/ml. Wool Cu concentration ranged from 2 to 8 mg/kg DM. Kidney Cu concentration ranged from 19.2 to 190 mg/kg DM. Over the 70 days of the experiment, the Cu retention for groups A - G were, respectively, 210 + 17, 680 + 149, 1191 + 39, 1054 + 20, 53 + 185, 1079 + 164 and 1225 + 157 mg. Liver Cu concentrations were, respectively, 718 + 174, 1186 + 176, 1440 + 248, 1522 + 477, 1740 + 212, 1560 + 46 and 1703 + 384 mg/kg DM. There was no correlation between total Cu intake and Cu retention in the body. However, there was a relationship between total Cu intake and liver Cu concentration ( r = 0.827 ) and between total Cu intake and faecal Cu concentration ( r = 0.997 ). Almost all of Cu output was excreted as a faecal Cu. Histopathological examination showed variable liver damage with some sheep showing single cell necrosis , particularly in the livers of sheep receiving 30% dried pig faeces in the diets. No kidney abnormalities were found. It was concluded that pig faeces, with no processing other than drying, are poorly utilized in the diet of sheep and with continuous feeding may induce copper toxicity.
  • Item
  • Item
  • Item
    Thumbnail Image
    Supplementary feeding of slow growing lambs
    Ikin, Terrence Leonard ( 1976)
    Mount Derrimut Field Station, approximately 320 ha, is situated 22.4 kilometers to the west of the Melbourne General Post' Office. It is operated by the Faculty of Agriculture and Forestry of the University of Melbourne, primarily for undergraduate teaching in Agricultural Science but also as a Centre for research. The climate is of a Mediterranean type with an average annual rainfall of 450 min., mainly of winter incidence. Typically the growing season begins about mid August and finishes in late November to early December. Soils are of volcanic origin and are mildly leached, ranging from shallow stoney red loams on the slopes to. moderately deep grey clays on the flats. The pastures are generally of improved types although there are some native species particularly in those paddocks with large areas of rocky outcrops. The 290 ha, of land available for cropping and grazing carry a herd of thirty crossbred beef cows plus about fifty followers of various ages and a flock of 500 Corriedale breeding ewes. Each year about 60 ha, are sown to wheat, barley and oats. Selection in the sheep flock has primarily been directed towards the genetic improvement of wool quality and lambing percentages: less attention has been paid to the improvement of the lamb growth rates. Over the past ten years considerable difficulty has been experienced in growing the lambs to prime condition, suitable for slaughter, by the time the pastures have matured towards the end of the spring growing season. The ewes were mated during early March so that they would lamb in August when the spring flush was occurring. The lambs then had about three months in which to grow to slaughter weight before the pastures matured. In recent years, mating has been changed to mid January, so that lambing would occur during June and. July. It was anticipated that this early mating, although possibly having an adverse effect on lambing percentages, would' allow the lambs a further four weeks of growth before pasture maturity. The strategy of early mating has in part improved the numbers of lambs in prime condition at the end of the season but there is still a variable number of lambs that are not in prime condition at the normal sale time. These lambs must either be carried over into the dry summer and sold in the following autumn, or sold at the normal time as store lambs at a considerably lower price. In 1973 investigations were started in an attempt to develop management strategies that would reduce or eliminate the number of Underweight lambs by the time of pasture maturity. Preliminary studies in which all lambs in the Mt. Derrimut flock were weighed at birth and at subsequent six week intervals, suggested that lambs that were lightweight at pasture maturity were also lightweight at six weeks of age. The correlation coefficient between six. week weight and the subsequent length of time required to reach slaughter weight was found to be -0.60. Although the lightweight lambs had lower birth weights than the lambs achieving slaughter weight at the normal. time, most of the advantage in weight of normal lambs was made during the first six weeks of life. Wardrop (1968) also found that in a prime lamb producing flock under southern Australian conditions, the correlation coefficient between liveweight at eight and seventeen weeks of age was 0.91. It was concluded that: (a) lambs that were lightweight at the normal sale time could be identified with reasonable confidence at about six weeks of age, and that (b) preferential treatment in the form of a concentrate diet offered sometime between six weeks of age and normal slaughter time, may reduce or eliminate the number of lambs carried-over beyond the end of the growing season. This thesis presents the results of studies designed to test these hypotheses.
  • Item
    Thumbnail Image
    Composition of commercial pig diets and utilization of piggery wastes
    Hilliard, Edward P ( 1977)
    The work presented in this thesis was part of an integrated study conducted by the School. of Agriculture and Forestry into various aspects of piggery waste utilization. Particular attention was given to the occurrence and source of mineral elements in pig diets and piggery wastes. Results of analysis of commercial pig diets and piggery wastes are discussed in relation to nutritional requirements and toxicities and from environmental and legislative aspects. The Literature Review in Chapter 2 describes how similarities in the atomic orbital configurations of some transition elements and oxy-anions can explain the synergisms and antagonisms displayed by these chemical entities in biological systems. In particular, the concept of orbital equivalence is used to explain some of the better known cases of mineral antagonisms affecting the health and nutrition of livestock. The antagonism between sulphate and molybdate ions is discussed relative to their ionic structures and to their respective involvements in copper metabolism. The interactions of copper, zinc and iron are examined, particularly in relation to pig nutrition. Interactions between copper, zinc and cadmium are related to their orbital structures and to their ability to form metallothioneins. The ability of high levels of copper and zinc to induce selenium deficiency in chicks is discussed and associated with the similar orbital configurations of zinc, copper and selenate ions. Caution is proposed in the formulation and mineral supplementation of multi-constituent diets used in intensive animal production. Procedures used in the development and calibration of analytical techniques for the determination of eleven elements in pig faeces and pig diets are described in Chapter 3. Copper, zinc, iron, cadmium, lead; sodium, potassium, magnesium, calcium and phosphorus were measured from a single sample digestion using a nitric-perchloric acid mixture. Phosphorus content in the digest was determined colorimetrically and the remaining elements by atomic absorption spectrometry. A separate digestion procedure was required for arsenic which was then measured by atomic absorption spectrometry after generation of arsenic as its hydride. Accuracy and precision of the techniques were rigorously tested using standard addition and recovery procedures- and comparison of values obtained after analysis of the U.S. National bureau of Standards Reference Material ''Orchard Leaves". Chapter 4 reports the chemical composition of pig diets, ingredients of diets and mineral-vitamin supplements collected from 24 commercial piggeries in Victoria. An evaluation of the diets relative to the suggested dietary mineral requirements for grower pigs proposed by the Agricultural Research Council (A.R.C.) indicated that mineral imbalances occurred in many of the diets. High levels of cadmium and lead found in some diets originated principally as contaminants of mineral additives and from meat meals, meat and bone meals and fish meals. The mineral content of the diets was found to be highly variable and indicated differences in choice of dietary ingredients and in the practice of mineral supplementation. Copper, zinc, and iron levels in the diets were particularly variable and in the case of zinc and iron were present at concentrations far in excess of the levels suggested by.the A.R.C. Chapter 5 describes the chemical composition and in vitro organic matter digestibility (OMD) of pig faeces samples collected from 24 piggeries in Victoria. Pig faeces are shown to be highly variable in chemical and nutrient content and, in some instances, to contain high levels of potentially toxic mineral elements such as copper, cadmium, lead and arsenic. Wide ranges in in vitro OMD values, proximate constituent concentrations and cell wall composition were also recorded. Multiple regression analysis associated low in vitro OMD with high values of cell wall content, phosphorus, copper and lignin/cell wall. Standard additions of phosphorus and copper to pig faeces samples undergoing in vitro fermentation significantly lowered the OMD values of these samples, contributing further evidence of the possible inhibitory effects of these elements to the digestive processes of the ruminant. Some health aspects of refeeding pig faeces as an ingredient in diets for ruminants are discussed, particularly in relation to the presence of toxic minerals such as copper, cadmium and lead. In Chapter 6 a procedure is described for calculating the chemical composition of pig manure using dietary composition, recommended feed intakes, published retention values for each element and estimated excreta outputs fin. an "average" pig of 45 kg liveweight. The variability in the calculated composition of manure is discussed in relation to existing and proposed guidelines limiting the rates of application of pig manure to land. Some aspects of the proposed guidelines for Victoria are discussed; particularly in relation to the suggested maximum rates of manure application to provide not more than 500 kg of nitrogen or 300 kg of potassium/hectare/ annum. Because of the range in the estimated nitrogen content of pig manures, the quantities of manure supplying 500 kg of nitrogen were calculated to range from 46 - 123 tonnes with an average of 63 tonnes. Included in these quantities were widely varying amounts of other elements which would be applied to land with 500 kg of nitrogen; some of which are known to pose environmental problems through leaching to ground water, as run-off to waterways or through ingestion by grazing animals. The potential environmental hazards of applying large amounts of minerals, including heavy metals, to land are discussed and a method is proposed which would permit a more accurate estimate of manure loading rates to provide 500 kg nitrogen/ hectare of land.
  • Item